Printing telegraph system



1939- E. THOMPSON ET AL 2,132,101

PRINTING TELEGRAPH SYSTEM Filed June 15, 19 56 2 Sheets-Sheet 1 ATTORNEY Dec. 5, 1939. A. E. THOMPSON ET AL. 2,182,101

PRINTING TELEGRAPH SYSTEM Filed June 13, 1936 2 Sheets-Sheet 2 80V LL 1/] A L:

Fig. 5.

Patented Dec. 5, 19 39 UNITED STATES PATENT OFFICE PRINTING TELEGRAPH SYSTEM Application June 13, 1936, Serial No. 85,016 In Great Britain July 19, 1935 8 illaims.

This invention relates to type printing telegraph systems and apparatus and has for its object to provide a form of combined regenerator and distributor applicable either to start- 5 stop or multiplex systems which shall be noiseless in operation, capable of working at high speeds and at the same time cheap to manufacture.

According to the invention the eiiect of a beam of radiation on a device sensitive thereto is controlled by the combined eilect of a rotating shaft and incoming signals.

The nature of the invention will be better understood from the following description taken in conjunction with the accompanying drawings which show different embodiments of the invention. Of these drawings, Y

Fig. 1 shows diagrammatically a receiving arrangement for a start-stop system in which the passage of a beam of light to a photo-electric cell is controlled by means of shutters;

Fig. 2 shows a similar arrangement in which the passage of the beam is controlled electrically;

Fig. 3 shows the circuit arrangements of a regenerative repeater according to the invention;

Fig. 4 is a diagrammatic elevation, and

Fig. 5 is a plan showing the arrangement of on a shaft m. The movable part of shutter is 1 controlled by a magnet 0 connected to the line L. The shutter e is normally open to allow pas- 40 condition of the magnet g the shutter f is closed.v For shutters e and fany well known form of light valve may be used.

The shaft m is coupled through a friction clutch F with a shaft ms constantly rotated by a motor. The shaft 112. is held from rotation by a stop arm n'engaging a detent 0 carried on the shaft.

The electrodes of the photo-electric cell are connected in circuit with a battery bb and the {grid of a grid-controlled gas discharge tube d in such manner that when light does not fall on the cathode of the cell c the tube d is not ignited but that excitation of the photo-electric cellwillraise the potential of thegrid of tube sage of the light but in the normally energised d sufflciently to initiate a'discharge therein. The anode of tube d is connected through normally closed contacts h to the brush of a distributor J. This brush is mounted on the shaft m and normally rests on a contact connected through a magnet l'to the positive pole of a high tension source the negative pole of which is connected to the cathode of tube d.

When magnet g de-energises consequent upon the arrival of a start signal, the shutter j is opened and light from the lamp a is allowed to fall on the photo-electric cell c. The consequent increase of potential on the grid of tube at initiates a discharge in thls'tube and the consequent fiow of anode current operates the magnet Z to withdraw the stop arm n from the detent 0.

At a predetermined interval after the commencement of rotation .of shaft m, the cam q thereon closes the shutter e and the cam p on the same shaft opens the contacts It thus extinguishing the discharge in tube d. The cam (31 is cut so as to open the shutter e for a brief interval in the middle of each signal element period. If during that interval the magnet g is receiving a marking signal the shutter is also open, light is allowed to pass to cell 0, tube 11 is ignited and anode current flows since the anode circuit is closed by the passage of the brush of distributor 'J over one of the next five contacts. These contacts'are connected to the respective magnets R1R5 of any well known form of multiple magnet printer. The cam 11 is cut to open the contacts h and so extinguish the discharge in tube 41 before the brush of dis- The last contact of distributor J is left unconnected, as the period during which the brush is passing over this contact corresponds to the stop period.

It is clear that many modifications could be made in the above-described arrangements within the scope of the invention. For example, instead of providing a separate magnet l to release the shaft m for rotation, the stop arm n could be removed from the detent o by mechanical means directly operated by the line magnet g. The brush distributor J could be replaced by a series of cam operated contacts.

It is clear also that the light from the lamp 1:. after passing shutters e and I could be renected by means of a mirror, mounted on the shaft m or deflected by the rotation of the shaft, on to five separate photo-electric cells, each connected to a separate gas discharge tube and to a separate one of the magnets Rl-RE.

Fig. 2 shows an arrangement similar to that of Fig. 1 in which, however, the mechanical shutters for interrupting the beam of light may be replaced by purely optical devices. The line L is connected directly-to one electrode of a Kerr cell 11.1 the other electrode of'which is connected to earth. The light from the lamp a is concentrated by lens 12 into a parallel beam and falls upon a shutter t1 provided with a narrow slit. The narrow beam thus produced, after polarization by a Nicol prism v or its equivalent, traverses the Kerr cell m. In the absence of potential applied to the Kerr cell 111 the beam of light traverses the Kerr cell and passes through a narrow slit in a second fixed shutter t1 and through a second Kerr cell uz. One electrode'of this latter is connected to earth potential and the other electrode is connected through contacts 1 to a source of potential s. If contacts 1 are open the beam traverses a slit in a shutter t3 and falls on the cathode of the photo-electric cell c. Illumination of cell c ignites a discharge in a gas-discharge tube at to allow current to flow through magnet l or one of the magnets R1-R5 as controlled by the distributor J. The contacts r are controlled by cam q on the shaft m.

Thus potential applied to the Kerr cell M2 by the cam controlled contacts 1' holds the beam of light deflected and consequently the line signals acting on the first Kerr cell 114, have no effect except at the moment of time when the cam controlled contacts are opened. 'It is quite clear that this arrangement could be reversed so that light would only reach the photo-electric cell when potential is applied to both 'Kerr cells.

Figs. 3, 4 and 5 show the arrangement for a regenerat'or for double current signalling. Figures 4 and'5 are respectively a diagrammatic elevation and plan of the arangements for controlling a beam of light from a source a on to two photo-electric cells P1'and P2. An image of this source a formed by a lens b is reflected by two mirrors Q1 and Q2 so that half falls upon one photo-electric cell P1 and half upon the other cell P2. Q2 is located a disc D mounted on the shaft m. This shaft is adapted to be driven through a friction clutch F from a constantly rotating shaft ms, but is normally held stationary by a stop arm n engaging a detent 0 on the shaft. The disc D is provided with a number of slots arranged so that the light from the source a can fall upon mirrors Q1 and Q2 during short intervals of time whilst the disc D makes one-revolution. One of the slots is opposite the mirrors Q1 and Q2 when the disc D is in the stationary position but this slot is shorter than the others so that light from the source a falls upon mirror Q2 only and so is reflected only on to the photo-electric cell P2, leaving the cell P1 in darkness.

The incoming line L1 is connected to a receiving relay 9 the contacts of which control the connection of potential to the photo-electric cells P1 and P2. The armature of this relay normally rests upon the contact connected to the cell P1.

The photo-electric cells P1 and P2 control the grid potentials of gas discharge tubes T1 and T2. On the arrival of a. start signal, the relay 9' in responding thereto connects potential to the photo-electric cell P: which is illuminated. Pas- Between the lens b and mirrors Q1 and sage of current through this cell raises the potential of the grid of tube Ta sufficiently to initiate a discharge therein. Current therefore news from the battery B through the lower winding of polarised relay M winding of m net M and winding of relay M2.

The polarised relay M3 reverses its contacts to v repeat the start signal into the outgoing line L2. The magnet M withdraws the stop arm n from the detent o and the shaft m begins to rotate. Illumination is removed from photo-electric cell Pa. The relay M2 closes its contacts ma which short-circuit the gas discharge tube T2 and extinguish the discharge. As relay M3 is polarised, the re-transmitting contact tongue remains in the last position into which it was moved.

During the receipt of the signal elements of a combination representing a character, the armature of relay 9 moves correspondingly to connect potential to one of the photo-electric cells P1 or P2 in accordance with thecharacter of the signal element. For a brief interval in the middle of each signal element, both cells P1 andPz are illuminated, current passes through the one to which potential is connected by the line relay 0 and a discharge is ignited in the corresponding gas discharge tube T1 or T2. The current flowing through the gas discharge tube energizes the upper or the lower winding of polarised relay M3 to repeat the signal element into line L2 and the relay M1 or Mr closes contacts m1 or mg to short circuit the tube T1 or T2 which was ignited and terminate the current therethrough.

Upon receipt of a stop signal the armature of the receivingv relay 9 connects potential to the cell -P1 thereby causing a discharge through tube T1. As magnet M is not connected in this circuit it will be de-energised and the stop arm n will engage withthe detent o and bring the shaft m to rest.

Contacts may be provided on the shaft 111. to

short circuit magnet M whilst the shaft is rotating and to remove the short circuit as the shaft approaches the stopping position, thus preventing the oscillation of the armature of the magnet M! whilst the shaft is rotating.

It is clear that an arrangement in which potential is connected to a single photo-electric cell graph system comprising a source of radiation,

a device sensitive to said radiation, means for directing a beam of said radiation upon said device, a telegraph line, means connected in said line for controlling the effect of said beam upon said device in accordance with signals in said line, a shaft means for rotating said shaft, means controlled by said shaft for causing said beam to be directed upon said device only for a brief interval in the middle of each signal period, means controlled by said device for initiating reproduction of each signal element, and independent means for determining the length of each reproduced element.

2. Receiving arrangement for a printing telegraph system comprising a photo-electric cell, means for directing a beam of light upon an electrode of said cell, a signal line, means connected in said line and controlled by signals electrode only on the occurrence of signals of certain character in said line, a shaft, means for rotating said shaft, means controlled by said shaft for allowing said beam to fall upon said electrode' only for a brief interval in the middle of each signal period,'means for causing current to pass through said cell when light falls upon it, means cooperating with said cell for generating a lengthened impulse for each such passage of current, a multiple magnet printer and means recting radiation from said source upon said device, a telegraph line, means connected in said line for allowing said radiation to fall upon said device only on the occurrence of signals of certain character in said line, a shaft, means for rotating said shaft, means controlled by said shaft for allowing said radiation to fall upon said device for a brief interval only in the middle of each signal period, a gas discharge tube, means associated with said device for initiating the passage of current through said discharge tube on radiation falling on said device, a multiple magnet printer, means controlled by said shaft when rotating for distributing the currents through said discharge tube to the magnets of said printer in proper sequence, and means for extinguishing the discharge in said gas discharge tube for each signal element period.

4. Receiving arrangement for a printing telegraph system comprising a line, a device sensitive to radiation, a shaft, means for rotating said shaft, means controlled by said shaft for directing radiation on to said device for a brief interval in the middle of each signal period, means connected in said'line for determining the pro: duction by said device responsive to said radiation of currents of character dependent upon the character of signals in said line, and means for reproducing from said currents regenerated signals of the same character as the signals in said line.

5. Receiving arrangement for a printing telegraph system comprising a device sensitive to radiation, means for directing a beam of radiation on to said device, a line, a first shutter in the path of said beam, a magnet connected in said line, means controlled by said magnet for opening said shutter, a shaft, means for rotating said shaft, a second shutter in the path of said beam, means controlled by said shaft for opening said second shutter, a gas discharge tube, means controlled-by radiation falling on said device for initiating a discharge in said gas discharge tube, means controlled bysaid shaft for terminating the discharge in said gas discharge tube, a multiple magnet printer, and means controlled by said shaft for distributing the currents through said gas discharge tube to the magnets.

of said printer.

6. Receiving arrangement for a printing telegraph system comprising means for directing a beam of polarised light on to a light sensitive element, a line, a Kerr cell inserted in said beam,

-means for impressing potentials from saidline across said Kerr cell to control the passage of polarised light therethrough, a shaft, means for rotating said shaft, a second Kerr cell inserted in said beam, means controlled by said shaft to control the passage of polarised light through said second Kerr cell, means controlled by said device for generating electric currents in re-' sponse to light falling upon it, a multiple magnet printer and means controlled by said shaft for distributing said currents to the magnets of said printer.

7. Regenerator for printing telegraph signals comprising a device sensitive to radiation consisting of two light sensitive cells, a shaft, means for rotating said shaft, means controlled by said shaft for directing a beam of light upon both said cells for a brief intervalin the middle of each signal element period, a line, a magnet in said line, means under control of said magnet for allowing current to pass through the respective cells dependent upon the character of signals in said line, a gas discharge tube connected to each of said cells, means responsive to current through a cell for initiating a discharge through the corresponding tube, a polarised relay having two windings, means responsive to a discharge through one of said tubes for passing current through a respective winding of said relay, means responsive to each said discharge for extinguishing the said discharge, a second line, and means controlled by said polarised relay for retransmitting signals to said second line.

8. Receiving arrangement for a printing telegraph system comprising a source of potential, a device sensitive to radiation and allowing current to pass therethrough from said source of potential when radiation falls upon it, means for directing a beam of radiation upon said device, a line, means connected in said line for controlling the eiiect of said beam of radiation on said device in accordance with signals in said line, a rotatable shaft, means controlled by said shaft for controlling the duration of time said radiation falls upon said device, a gas discharge tube, means responsive to currents in said device for initiating a discharge through said gas discharge tube, and means responsive to said discharge for reproducing said signal. 

